Hearing Loss Correlates With Cognitive Decline
Aging is a global phenomenon, occurring throughout the body, which is why correlations between the pace of different manifestations of degenerative aging are likely to happen and not necessarily linked by anything other than the fundamental causes of aging:
[Researchers] studied 1,984 older adults (average age about 77 years) enrolled in a prospective observational study that began in 1997-1998. A total of 1,162 individuals with baseline hearing loss had annual rates of decline in test scores that measured global and executive function that were 41 percent and 32 percent greater, respectively, than those among individuals with normal hearing. Compared to those individuals with normal hearing, individuals with hearing loss at baseline had a 24 percent increased risk for incident cognitive impairment, according to the study results."Our results demonstrate that hearing loss is independently associated with accelerated cognitive decline and incident cognitive impairment in community-dwelling older adults," the authors comment. "The magnitude of these associations is clinically significant, with individuals having hearing loss demonstrating a 30 percent to 40 percent accelerated rate of cognitive decline and a 24 percent increased risk for incident cognitive impairment during a six-year period compared with individuals having normal hearing."
The authors suggest that, on average, individuals with hearing loss would require 7.7 years to decline by five points on the 3MS (the Modified Mini-Mental State Examination, a commonly accepted level of change indicative of cognitive impairment) compared with 10.9 years in individuals with normal hearing.
Link: http://www.eurekalert.org/pub_releases/2013-01/jaaj-hlm011713.php
The conclusions offered here (and in a linked abstract) seem to be not fully warranted. The observed decline in mental capacity among the older individuals with a sensori-neural hearing loss documented at the onset of the study (as opposed to the folks with normal hearing) is rather meaningless without a commentary on the origin of hearing loss.
By and far, the most common reason for hearing loss in older men is their lifetime exposure to noise. In effect, the study took a cohort made of factory workers, miners, soldiers etc and compared them to a group of white collar workers.
It doesn't take this study to know that social status, education, bilingualism and other factors of similar nature delay dementia.
It would be quite easy to increase the value of this study by testing the subjects' hearing at the end of the period of observation. By then, majority of them would be over 10 years into retirement and removed from their noise work environment. Why wasn't it done? Hearing test would take no more than 10 minutes.
I am bit disappointed to see poorly designed clinical studies here, while I am impressed daily with the information concerning molecular sciences.
Alex Modz
Alex,
I'm tempted by a view opposite to yours, and which might be a somewhat more extreme version of the claim made by the study: in the case of one late-fifty-ish nieghbour of mine it seems to me that his problem with hearing is precisely that he is too stupid to understand what is said.
The good news from the point of view of aging research, however, is that this may not be a manifestation of aging. It is entirely possible that the man was just that stupid long before I knew him.
-dlj.